• Radiation Oncology Journal
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• v.4 no.2
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• pp.135-139
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• 1986

Seven patients having midline granuloma received local irradiation from March 1983 to June 1986. Clinically, all of the 7 patients had pansinusitis with necrotic destruction of the involved sites and one case revealed colonic lesion. Each of the patients received a tumor dose of $4,000\~5,000 cGy/5\~6$ wks to the upper aerodigestive tract using a 6-MV linear accelerator. Complete and partial remission occured in 3 patients each, and in one case, the disease progressed despite of the irradiation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.612-622
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• 2002

In this paper, we review temporal error concealment for video transport over unreliable networks, and a new approach for the recovery of lost or erroneous motion vection(MV)s by classifying the movements of neighboring blocks by their homogeneity is proposed. MVs of the neighboring blocks are classified according to the direction of MVs and a representative value for each class is determined to obtain the candidate MV set. By computing the distortion of the candidates, a MV with the minimum distortion is selected. Experimental results show that the proposed algorithm exhibits better performance in many cases than existing methods.

• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.367-373
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• 1995

The cDNAs derived from the coat protein (CP) genes of six plant RNA viruses, tobacco mosaic virus-pepper strains (TMV-P) and -ordinary strain (TMV-OM), potato virus Y (PVY), turnip mosaic virus (TuMV), cucumber mosaic virus (CMV) and potato leafroll virus (PLRV), were subcloned into the transcription vector, pSPT18, containing SP6 and T7 promoters. The digoxigenin (DIG)-labeled RNA polymerase after linearlization of the cloned pSPTs with XbaI or SacI, and were tested for their sensitivities for the detection of the six viruses. In slot-blot hybridization, dilution end points for the detection of TMV-P and TMV-OM were 10-4, while those of PVY, TuMV and CMV were 10-3. PLRV was detected at the dilution of 10-2. When each RNA probe was applied for the detection of the viruses in the preparations from the leaf disks (8 mm in diameter, and 12 to 15 mg in weight) of infected natural host plants, TMV-P, TMV-OM and TuMV could be detected from one disk, while PVY from 1 or 2 disks. CMV was detected in the preparation from two disks, and PLRV from three disks. With DIG-labeled RNA probe, PVY was detected at 5 days after inoculation, but with ELISA the virus was detected at 8 days after inoculation to tobacco (Nicotiana tabacum cv. Xanthi nc) plants on which symptoms appeared at 9 days after inoculation. No difference was observed in cross reaction between the RNA probes for the detection of TMV-P and TMV-OM.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.33-36
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• 2011

The genome of a potyvirus isolate associated with chlorotic spots and vein banding symptoms on Spathiphyllum spp., in Andhra Pradesh state, India was amplified by RT-PCR using degenerate potyvirus primers, amplicons cloned, and sequence (1.6 kb) analyzed. This virus isolate shared maximum identity of 74.8% and 80.2% at coat protein (CP) gene nucleotide (906 nucleotides) and amino acid (302 amino acids) levels, respectively with Dasheen mosaic virus (DsMV)-M13 isolate reported from China. But its 3'-UTR (258 nucleotides) had maximum identity of 62.5% with DsMV-Vietnam isolate. The deduced molecular weight of CP is 33.57 kDa and it contained DAG triplet in its N-terminal region. In CP amino acid based phylogenetic analysis, this virus isolate represented a separate branch but closer to DsMV isolates cluster. Based on the molecular criteria set for the discrimination of species and genus in the Potyviridae family, the present virus isolate was identified as a distinct virus species in the genus Potyvirus and proposed the name Spathiphyllum chlorotic vein banding virus (SCVbV).

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.336-340
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• 2015

Background: Potentially harmful unplanned extubation (UE) may occur in patients on mechanical ventilation (MV) in an intensive care unit (ICU) setting. This study aimed to evaluate the clinical characteristics of UE and its impact on clinical outcomes in patients with MV in a medical ICU (MICU). Methods: We retrospectively evaluated MICU data prospectively collected between December 2011 and May 2014. Results: A total of 468 patients were admitted to the MICU, of whom 450 were on MV. Of the patients on MV, 30 (6.7%) experienced UE; 13 (43.3%) required reintubation after UE, whereas 17 (56.7%) did not require reintubation. Patients who required reintubation had a significantly longer MV duration and ICU stay than did those not requiring reintubation ($19.4{\pm}15.1days$ vs. $5.9{\pm}5.9days$ days and $18.1{\pm}14.2days$ vs. $7.1{\pm}6.5days$, respectively; p<0.05). In addition, mortality rate was significantly higher among patients requiring reintubation than among those not requiring reintubation (54.5% vs. 5.9%; p=0.007). These two groups of patients exhibited no significant differences, within 2 hours after UE, in the fraction of inspired oxygen, blood pressure, heart rate, respiratory rate, and pH. Conclusion: Although reintubation may not always be required in patients with UE, it is associated with a poor outcome after UE.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.56-56
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• 2003

For the treatment of superficial tumors like squamous cell carcinoma of the head and neck, 6 MV photon beam is not appropriate and a spoiler is widely used to increase dose in the buildup region, while preserving the skin sparing effect. However, commercially available treatment planning systems assume a normal unspoiled beam, thereby cannot predict the buildup dose with spoiler accurately. We aimed to implement a Monte Carlo (MC) based planning system to apply it to the radiation treatment of head and neck. Lucite with thickness of 10-mm was used for the beam spoiler with Siemens Primus 6 MV photon beam. BEAM/DOSXYZ MC system was employed to model the linac and the spoiler. To verify the calculation accuracy of MC simulations, the percent depth doses (PDDs) and profiles with and without spoiler were measured using a parallel-plate chamber. For the MC based planning, we adopted a hybrid interface system between Pinnacle (Philips, USA) and BEAM/DOSXYZ to support treatment parameters of Siemens linac and the spoiler. The measurements of PDDs and profiles agreed with the corresponding MC simulations within 2% (lSD), which demonstrate the reliability of our MC simulations. The spoiler generated electrons make a contribution to the absorbed dose up to depth of 2cm, which shows that the dominant source of increased dose from spoiler system is the contaminating electrons created by the spoiler. The whole procedures necessary for MC based treatment planning were performed seamlessly between Pinnacle and BEAM/DOSXYZ system. This ability helps to increase the clinical efficiency of the spoiler technique. In conclusion, we implemented a MC based treatment planning system for a 6 MV photon beam with a spoiler. We demonstrate sophisticated MC technique makes it possible to predict dose distributions around buildup region accurately.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1458-1469
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• 2018

This paper proposes a novel common-mode voltage (CMV) elimination (CMV-EL) method based on model predictive control (MPC) to eliminate CMV for three-level T-type inverters (3LT2Is). In the proposed MPC method, only six medium and one zero voltage vectors (VVs) (6MV1Z) that generate zero CMV are considered as candidates to perform the MPC. Moreover, the influence of dead-time effects on the CMV of the MPC-based 6MV1Z method is investigated, and the candidate VVs are redesigned by pre-excluding the VVs that will cause CMV fluctuations during the dead time from 6MV1Z. Only three or five VVs are included to perform optimization in every control period, which can significantly reduce the computational complexity. Thus, a small control period can be implemented in the practical applications to achieve improved grid current performance. With the proposed CMV-EL method, the CMV of the $3LT^2Is$ can be effectively eliminated. In addition, the proposed CMV-EL method can balance the neutral point potentials (NPPs) and yield satisfactory performance for grid current tracking in steady and dynamic states. Simulation and experimental results are presented to verify the effectiveness of the proposed method.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.113-115
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• 2002

The Monte Carlo simulation method is a numerical solution to a problem that models objects interacting with other objects or their environment based upon simple object-object or object-environment relationships. In spite of its great accuracy, It was turned away because of long calculation time to simulate a model. But, it is used to simulate a linear accelerator frequently with the advance of computer technology. To simulate linear accelerator in Monte Carlo simulations, there are many parameters needed to input to Monte Carlo code. These data can be supported by a linear accelerator manufacturer. Although the model of a linear accelerator is the same, a different characteristic property can be found. Thus, we performed a commissioning process of 6MV photon beam in Varian 2300C/D model with BEAM/EGS4 Monte Carlo code. The head geometry data were put into BEAM/EGS4 data. The mean energy and energy spread of the electron beam incident on the target were varied to match Monte Carlo simulations to measurements. TLDs (thermoluminescent dosimeter) and radiochromic films were employed to measure the absorbed dose in a water phantom. Beam profile was obtained in 40cm${\times}$40cm field size and Depth dose was in 10cm${\times}$10cm. At first, we compared the depth dose between measurements and Monte Carlo simulations varying the mean energy of an incident electron beam. Then, we compared the beam profile with adjusting the beam radius of the incident electron beam in Monte Carlo simulation. The results were found that the optimal mean energy was 6MV and beam radius of 0.1mm was well matched to measurements.

• Radiation Oncology Journal
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• v.7 no.1
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• pp.113-121
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• 1989

The inclusion of air filled cavities in treatment fields creates a potential dosimetric problem due to the rebuildup phenomenon near the air-tissue interface using a simulated phantom, such as air gap, air cylinder, and air cavity, the amount of rebuldup along the various field sizes and air cavity dimensions was measured. The results are as follows. 1. As the field size becomes larger in comparison with the cavity size, or as the cavity size gets bigger when the field size is equal to the cavity size, rebuildup decreases. 2. When the distance between the phantom surface and the air cavity is less than 1.5cm, there is prominent rebuildup. And when the distance is more than 1.5cm, rebuildup is relatively constant, 3. The change according to the depth of the cavity is affected by the field size and the cavity size, rebuildup usually increases when the depth of the cavity increases. 4. It is suggested that tissue equivalent material should be applied on the skin to make tissue thickness over the air cavity more than 1.5cm and that the field size should include the air cavity with at least 1cm margin.

• Progress in Medical Physics
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• v.29 no.2
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• pp.66-72
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• 2018

The proper position of a multi-leaf collimator (MLC) is essential for the quality of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) dose delivery. Task Group (TG) 142 provides a quality assurance (QA) procedure for MLC position. Our study investigated the QA validation of the mechanical leaf gap measurement and the maintenance procedure. Two $VitalBeam^{TM}$ systems were evaluated to validate the acceptance of an MLC position. The dosimetric leaf gaps (DLGs) were measured for 6 MV, 6 MVFFF, 10 MV, and 15 MV photon beams. A solid water phantom was irradiated using $10{\times}10cm^2$ field size at source-to-surface distance (SSD) of 90 cm and depth of 10 cm. The portal dose image prediction (PDIP) calculation was implemented on a treatment planning system (TPS) called $Eclipse^{TM}$. A total of 20 VMAT plans were used to confirm the accuracy of dose distribution measured by an electronic portal imaging device (EPID) and those predicted by VMAT plans. The measured leaf gaps were 0.30 mm and 0.35 mm for VitalBeam 1 and 2, respectively. The DLG values decreased by an average of 6.9% and 5.9% after mechanical MLC adjustment. Although the passing rates increased slightly, by 1.5% (relative) and 1.2% (absolute) in arc 1, the average passing rates were still within the good dose delivery level (>95%). Our study shows the existence of a mechanical leaf gap error caused by a degenerated MLC motor. This can be recovered by reinitialization of MLC position on the machine control panel. Consequently, the QA procedure should be performed regularly to protect the MLC system.